The present invention relates generally to an apparatus for identifying the need to replace ropes constructed of synthetic fibers, preferably of ropes of aromatic polyamide.
From the European patent document EP 0 731 209 A1 a device for identifying the need to replace a stranded fiber rope is known. The stranded rope consists of several layers of high-tensile synthetic fibers, the layers being laid over each other and surrounded by a firmly bonding rope sheath. To make identification of the maximum allowable internal rope wear possible, the extruded sheath of the rope has different colors arranged coaxially. The rope sheath indicates abrasive wear that occurs on driving, or driven, ropes as a result of the slipping that occurs on the traction sheave due to differences in force. Experimental values are used to correlate the abrasive wear of the sheath, by reference to the defined running surface of the ropes in the traction sheave, to the state of wear in the interior of the ropes. Accordingly, as soon as the underlying color is visible, this is taken to indicate that the interior of the rope is worn to the maximum allowable extent, and that the rope must be replaced within a specified remaining period of time.
With the device for identifying the need to replace synthetic fiber ropes described so far, the state of the rope can be easily assessed by means of a simple visual check of the rope sheath. However, the indication obtained in this indirect manner depends on experimental values; it does not allow a statement to be made concerning the precise internal condition of the rope. Rope wear due to, for example, such factors as premature material fatigue, short-term overloading, or external influences is not taken into consideration.
The problem underlying the present invention is that of proposing a device for identifying the need to replace ropes which reliably indicates the true state of wear.